Rehabilitation of a mouth and restoration of missing teeth using dental implants and dental prostheses are known. A dental implant is a surgical component that interfaces with the bone to support a dental prosthesis such as a crown, bridge, denture, facial prosthesis or to act as an orthodontic anchor. The dental implants are made of materials, such as titanium, that can form an intimate bond to bone. The implant is first implanted in the bone of the jaw, after which a dental prosthesis is added. Dental implants in the bone are used as an anchorage, support and retention for the different dental prostheses.
Many types of implants exist, each with a different design, size and connection element. The connection element of an implant is used to connect the prostheses to the implant directly or indirectly. Different connection elements may be found in different implants. The prostheses may be directly screwed to the implant, or alternatively it may be screwed or cemented to another prosthetic component connected to the implant.
Each prosthesis must fit to specific needs and thus must be precise and must fit exactly to the specific implant. In order to ensure the accuracy of the manufactured prosthesis, it is of great importance to transfer the exact location, angulation and degree of rotation (i.e. “timing”) of dental implants from the patient's mouth to the plaster model.
In order to create the dental prosthesis, an impression of the jaw, having the location and angulation of the dental implants (and any existing teeth), is created by the physician in the clinic. This impression is used later to create the plaster model from which the prosthesis is fabricated in the laboratory.
A common technique for taking an impression of the mouth is the closed tray technique, as described in FIGS. 1-5, to which reference is now made. FIG. 1 schematically illustrates a dental arch with two straight implants 14, implanted into bone 10, below gingiva 12.
In order to fabricate an accurate model, it is crucial to copy the exact location of the implants, the teeth and any soft tissue around and between the implants and the teeth. In particular, it is of great importance to copy the exact location, angulation and rotation (called “timing” in the professional terminology) of the dental implants. In one commonly used technique to copy the exact location, angulation and timing of implants 14, metal components 16 are screwed into each implant 14 and a plastic cap 18 is snapped onto metal component 16. As a result, metal components 16 protrude above bone 10 and gingiva 12. The combined plastic cap 18 and metal component 16 is known as a “transfer” element.
FIG. 2 shows plastic caps 18 snapped onto each metal component 16. FIG. 2 also shows an impression material 22, made of an elastomeric material, placed in an impression tray 20, to be pressed over the structures to be copied in the mouth (FIG. 3). As can be seen, elastomeric impression material 22 surrounds plastic caps 18. When elastomeric impression material 22 hardens, it becomes rigid, trapping plastic caps 18 therein.
After elastomeric impression material 22 has hardened, the dentist releases it from the mouth, as illustrated in FIG. 4. Released impression material 22 contains plastic caps 18 loosened from metal components 16 to which they were connected. Impression material 22 thus has the exact shape of the dental arch, which includes the shape of gingiva 12 and the shape and location of any existing teeth (not shown in the figures for simplicity), as well as the exact location, angulation and timing of each implant 14, as indicated by plastic caps 18.
As shown in FIG. 5, after removing impression material 22, metal components 16 are unscrewed from dental implants 14. Removed metal components 16 are then screwed into implant analogs 54 which have the same connection type as the implants that remain in the patient's mouth, and the resultant structures, built of removed metal components 16, and implant analogs 54, are snapped into plastic caps 18 immersed in rigid impression material 22. The resultant structure is ready to be used for standard fabrication of a dental plaster model in the dental laboratory. Implant analogs 54 may have any suitable shape and structure, as is known.